Significance of decoy receptor 3 (Dcr3) and external-signal regulated kinase 1/2 (Erk1/2) in gastric cancer

Abstract

Background: Decoy receptor 3 (DcR3), a member of the tumor necrosis factor receptor (TNFR) superfamily, is associated with anti-tumor immunity suppression. It is highly expressed in many tumors, and its expression can be regulated by the MAPK/MEK/ERK signaling pathway. The MAPK/MEK/ERK pathway has been reported to be a regulator in tumor occurrence, development and clonal expansion. External-signal regulated kinase (ERK) is a vital member of this pathway.

Results: The expression of DcR3 and ERK1/2 in tumor tissues of gastric cancer patients was significantly higher than the non-cancerous group (P < 0.05). There was no statistical difference among tumor tissues from patients with different ages or gender, and even of different differentiation (P > 0.05). However, in patients with stage I gastric cancer, the DcR3 and ERK1/2 levels were significantly lower than patients with more advanced stages.

Conclusions: DcR3 and ERK1/2 play a vital role in the development of gastric cancer, and they may be new markers for indicating the efficiency of gastric cancer treatment in the future.

Figure 1

The expression of DcR3 in gastric cancer and non-cancerous tissues analyzed by RT-PCR (Figure1a) and Western blotting (Figure1b). a: Lane M, DNA markers; lanes1-7, tumor tissues; lane 8, non-cancerous tissues; DcR3 mRNA was positive in 36 of 50 tumor tissues (1–7) and negative in non-cancerous tissues (8). b: lanes1-7, tumor tissues; lane 8, non-cancerous tissues. DcR3 protein was positive in 37 of 50 samples of tumor tissue (1–7), which only 3 of 50 in non-cancerous tissues (8).

Figure 2

The expression of ERK1/2 in gastric cancer and non-cancerous tissues analyzed by RT-PCR (Figure 2a) and Western blotting (Figure 2b). a: Lane M, DNA markers; lanes1-7, tumor tissues; lane 8, non-cancerous tissues; ERK1 and ERK2 mRNA were positive in tumor tissues. b: ERK1 and ERK2 protein were positive in tumor tissues (1–8).

Figure 3

The location of ERK1/2 protein in gastric cancer tissues analyzed by immunohistochemistry. A: Control, B: ERK1, C: ERK2.

Figure 4

The expression of DcR3 and ERK1/2 in mouse models analyzed by RT-PCR (Figure 4a) and Western blotting (Figure 4b). a: Lane M, DNA marker; lanes1-6, hearts, livers, spleens, lungs, kidneys and tumor tissues of mouse models on the fourth day; lanes7-12, which on the eighth day ; lanes13-18, on the twelfth day; ERK1 mRNA was positive in lane2,8,9,12,14,15,18, ERK2 mRNA was positive in lane1,2,6,9,10,12,13,14,15,17,18. DcR3 mRNA was detected in lane8, 12, 13, 14, 15, 16, 17, 18. b: lane 1, heart; lane2, liver; lane3, spleen; lane4,lung; lane5, kidney; lane6, tumor tissues; The expression of ERK1 protein increased in tumor tissues as time went on, in heart, liver and kidney persisted for 12 days, The expression of ERK2 could be detected in spleen and tumor from the second day which was positive in tumor tissues till the fourth day and all of five organs to the twelfth day. The expression of DcR3 protein was positive in tumor tissues and liver on the sixth day and in spleen on the tenth day, which was negative in heart, lung, kidney until the twelfth day.

Figure 5

The expression of ERK1/2 and P-ERK1/2 in BGC823 cell line with plasmid interference and inhibitor detected by Western blotting. a: The expression levels of ERK1/2 and P-ERK1/2 declined compared with the control. 1) control group; 2) 5:2 (plasmid: reagent); 3) 6:2 (plasmid: reagent). b: ERK1/2 phosphorylation gradually declined as the concentrations of the inhibitor U0126, PD98059 increased, but total ERK1/2 protein expression hardly changed. 1) 0 μmol/L; 2) 5 μmol/L; 3) 10 μmol/L; 4) 20 μmol/L; 5) 40 μmol/L. c: ERK1/2 phosphorylation gradually declined as the concentrations of the inhibitor APDC. 1) 0 μmol/L; 2) 10 μmol/L; 3) 20 μmol/L; 4) 40 μmol/L; 5) 80 μmol/L. d: PD98059 can obviously inhibit the MEK1/2 phosphorylation level, but it did not alter MEK1/2 or NF-κB expression levels. 1) 0 μmol/L; 2) 5 μmol/L; 3) 10 μmol/L; 4) 20 μmol/L; 5) 40 μmol/L.

Figure 6

The expression of DcR3 protein with plasmid interference and inhibitor by ELISA analysis. a: DcR3 expression levels in BGC823 culture supernate decreased when cells were treated with ERK1 interference plasmid. b: DcR3 expression levels decreased when cells were treated with ERK2 interference plasmid. c: DcR3 expression levels decreased when cells were treated with different concentrations of U0126, PD98059 and APDC μmol/L.